Design of graphene and nanotubes from aromatic compounds: a theoretical study.

A group of aromatic compounds (benzene, naphthalene, anthracene, and tetracene) was selected to design four sheets of graphene based on quantum mechanics calculations using the density function theory (DFT), leaning on the cyclic polymerization mechanism. Theoretical results offer that graphene-I is the most stable depending on the values of EHOMO (- 4.91601 eV), gap energy (2.76549 eV), and total energy (- 3447.42377654 a.u.). The thermodynamic theoretical outcome showed that all reactions are exothermic and spontaneous. Graphene is a two-dimensional plane, so the nanotube design process is with two possibilities: the first about the x-axis (horizontal (H)) and the second about the y-axis (vertical (V)). The theoretical results gave two groups: the first gave more stability to graphene at the expense of the nanotubes prepared from it, namely, graphene-I and the second gave less stability to graphene compared to the nanotubes prepared from it, namely, graphene-II, graphene-III, and graphene-IV), depending on the energy of HOMO and gap energy. The value of gap energy ranged (from 1.10370 to 1.79922 eV) for the following compounds (graphene-II, nanotube-II-V, nanotube-III-H, and nanotube-IV-V), making those important compounds in solar cells. These theoretical results showed the possibility of preparing graphene and then nanotubes from aromatic compounds, giving the benefit of doubling the preparation of new compounds with important applications and at the same time eliminating aromatic compounds harmful to the environment.